diff --git a/doc/bugs/mathjax_doesn__39__t_work_anymore_after_upgrade.mdwn b/doc/bugs/mathjax_doesn__39__t_work_anymore_after_upgrade.mdwn
index bd58eb23e..f47c5086b 100644
--- a/doc/bugs/mathjax_doesn__39__t_work_anymore_after_upgrade.mdwn
+++ b/doc/bugs/mathjax_doesn__39__t_work_anymore_after_upgrade.mdwn
@@ -25,3 +25,7 @@ The rebuild of an old site containing math is missing the following lines:
      <hr>
      </noscript>
 
+----------------------
+
+I finally noticed that the `page.tmpl` was messed up. It seams that the upgrade deleted the relevant `mathjax` line. Adding this makes it work again. Thanks!
+